We have synthesized CaBaLaCu3O7−δ and related compounds Ca0.9BaLaCu3O7−δ, Ca11 BaLaCu3O7−δ and Ca0.9Ce0.1 BaLaCu3O7−δ in order to investigate the effect of doping and non-stoichiometry at Ca-sites on the superconducting behaviour of tetragonal superconductor CaBaLaCu3O7−δ. The superconducting transition temperature (Tc) of Ca0.9 BaLaCu3O7−δ is the same as that of pure CaBaLaCu3O7−δ(67 ± 1 K). Calcium excess compound Ca1.1 BaLaCu3O7−δ showed a drop inTc to 72 K while the cerium-substituted compound Ca0.9 Ce0.1 BaLaCu3 O7−δ showed a drop inTc to 43 K. The results are explained on the basis of difference in valency between the host and the dopant ion.